function Person(name, age) {
    this.name = name,
    this.age = age,
    this.setName = function () {
        console.log('setname')
    }
    this.setAge = function() {
      console.log('进来')
    }
  }
  Person.prototype.setAge = function () {}
  function Student(name, age, price) {
    Person.call(this, name, age)  // 相当于: this.Person(name, age)
    /*this.name = name
    this.age = age*/
    this.price = price
  }
  var s1 = new Student('Tom', 20, 15000)
  s1.setName()
  debugger
  console.log(s1)
//   console.log(s1.setAge())